@import "https://fonts.cdnfonts.com/css/aptos";:root{--canvas:oklch(97.3% .006 248);--surface:oklch(99.5% .004 248);--panel:oklch(94.6% .008 248);--panel-2:oklch(91.8% .012 248);--ink:oklch(23.5% .018 248);--muted:oklch(46.5% .022 248);--soft:oklch(66% .019 248);--line:oklch(87% .012 248);--blue:oklch(53% .18 255);--blue-dark:oklch(43% .16 255);--blue-soft:oklch(93% .035 255);--green:oklch(53% .12 153);--green-soft:oklch(94% .04 153);--red:oklch(56% .16 24);--red-soft:oklch(94% .035 24);--amber:oklch(76% .13 82);--shadow:0 18px 48px oklch(28% .03 248/.09);--shadow-sm:0 8px 22px oklch(28% .03 248/.07)}*{box-sizing:border-box}html{background:var(--canvas)}body{background:linear-gradient(180deg,var(--canvas),oklch(95.5% .012 248));color:var(--ink);-webkit-font-smoothing:antialiased;text-rendering:optimizelegibility;margin:0;font-family:Aptos,Segoe UI,-apple-system,BlinkMacSystemFont,system-ui,sans-serif}button{font-family:inherit}.workspace{grid-template-columns:324px minmax(0,1fr);min-height:100vh;display:grid}.sidebar{border-right:1px solid var(--line);background:linear-gradient(oklch(96.5% .01 248),oklch(94% .012 248));flex-direction:column;gap:16px;height:100vh;padding:18px 14px;display:flex;position:sticky;top:0;overflow:auto}.workspaceName{color:var(--ink);align-items:center;gap:10px;padding:10px 12px;font-size:18px;font-weight:700;display:flex}.workspaceName svg{color:var(--blue)}.search{color:var(--muted);background:var(--surface);border:1px solid var(--line);box-shadow:var(--shadow-sm);border-radius:12px;align-items:center;gap:10px;padding:11px 12px;font-size:13px;display:flex}.courseMeter{background:var(--surface);border:1px solid var(--line);box-shadow:var(--shadow-sm);border-radius:18px;padding:14px}.meterTop{color:var(--muted);justify-content:space-between;align-items:center;gap:14px;font-size:12px;font-weight:700;display:flex}.meterTop b{color:var(--ink);font-size:14px}.meterTrack{background:var(--panel-2);border-radius:99px;height:8px;margin-top:12px;overflow:hidden}.meterFill{border-radius:inherit;background:linear-gradient(90deg,var(--blue),oklch(64% .14 244));width:10%;height:100%;transition:width .22s cubic-bezier(.22,1,.36,1)}.lessonNav{flex-direction:column;gap:5px;display:flex}.lessonNav p{color:var(--soft);text-transform:uppercase;letter-spacing:.08em;margin:8px 10px 6px;font-size:11px;font-weight:800}.lessonNav button{color:var(--ink);text-align:left;cursor:pointer;font:inherit;background:0 0;border:1px solid #0000;border-radius:14px;grid-template-columns:34px 1fr auto;align-items:center;gap:10px;min-height:56px;padding:9px 10px;transition:background .18s,border-color .18s,transform .18s,box-shadow .18s;display:grid}.lessonNav button:hover{border-color:var(--line);background:oklch(98.2% .006 248)}.lessonNav button:focus-visible,.option:focus-visible,.scoreBtn:focus-visible,.resetBtn:focus-visible,.pagerBtn:focus-visible{outline:2px solid var(--blue);outline-offset:3px;box-shadow:0 0 0 4px oklch(53% .18 255/.14)}.lessonNav button.active{background:var(--surface);box-shadow:var(--shadow-sm);border-color:oklch(82% .05 255);transform:translate(2px)}.pageIcon{background:var(--panel);border:1px solid var(--line);width:34px;height:34px;color:var(--muted);border-radius:10px;flex:none;place-items:center;display:grid}.lessonNav button.active .pageIcon{background:var(--blue-soft);color:var(--blue-dark);border-color:oklch(82% .08 255)}.lessonNav b{margin-bottom:2px;font-size:13.5px;font-weight:700;display:block}.lessonNav span{-webkit-line-clamp:2;color:var(--muted);-webkit-box-orient:vertical;font-size:12.5px;line-height:1.3;display:-webkit-box;overflow:hidden}.lessonStatus{background:var(--line);border-radius:50%;width:8px;height:8px}.lessonNav button.active .lessonStatus{background:var(--blue)}.sidebarFooter{color:var(--muted);align-items:flex-start;gap:9px;margin-top:auto;padding:12px;font-size:12.5px;line-height:1.35;display:flex}.sidebarFooter svg{color:var(--blue);flex:none;margin-top:1px}.contentShell{min-width:0}.topbar{border-bottom:1px solid var(--line);-webkit-backdrop-filter:blur(18px);backdrop-filter:blur(18px);z-index:5;background:oklch(99% .004 248/.88);justify-content:space-between;align-items:center;gap:18px;height:58px;padding:0 clamp(18px,5vw,72px);display:flex;position:sticky;top:0}.topbar span{color:var(--blue-dark);font-size:13px;font-weight:800}.topbar b{color:var(--muted);font-size:13px}.lessonPage,.emptyState{max-width:1240px;margin:0 auto;padding:52px clamp(20px,5vw,72px) 84px}.docHeader{max-width:880px}.docIcon{background:linear-gradient(145deg,var(--blue-soft),oklch(96.8% .012 248));width:58px;height:58px;color:var(--blue-dark);box-shadow:var(--shadow-sm);border:1px solid oklch(84% .05 255);border-radius:16px;place-items:center;margin-bottom:20px;display:grid}.lessonMeta{flex-wrap:wrap;gap:8px;margin:0 0 14px;display:flex}.pill{border:1px solid var(--line);background:var(--surface);color:var(--muted);border-radius:999px;align-items:center;gap:6px;padding:6px 10px;font-size:12px;font-weight:700;display:inline-flex}.pill.live{color:var(--green);background:var(--green-soft);border-color:oklch(82% .08 153)}.kicker,.sectionLabel{color:var(--soft);text-transform:uppercase;letter-spacing:.09em;margin:0 0 10px;font-size:12px;font-weight:800}h1,h2,h3{color:var(--ink);margin:0}h1{letter-spacing:-.04em;max-width:760px;font-size:46px;font-weight:800;line-height:1.06}h2{letter-spacing:-.03em;margin-bottom:15px;font-size:30px;font-weight:800;line-height:1.12}h3{letter-spacing:-.015em;font-size:17px;font-weight:750}.intro{color:var(--muted);max-width:760px;margin:18px 0 0;font-size:19px;line-height:1.62}.callout,.lockedBanner{background:var(--surface);border:1px solid var(--line);max-width:880px;box-shadow:var(--shadow-sm);border-radius:18px;gap:14px;margin:30px 0;padding:18px 20px;display:flex}.callout{background:linear-gradient(180deg,var(--green-soft),var(--surface));border-color:oklch(83% .055 153)}.callout svg{color:var(--green);flex:none}.lockedBanner{color:var(--muted);box-shadow:none;background:oklch(95.5% .011 248);border-style:dashed;align-items:center;margin:24px 0 0}.callout p{color:var(--muted);max-width:72ch;margin:4px 0 0;line-height:1.55}.twoCol{grid-template-columns:minmax(0,1fr) minmax(320px,.76fr);gap:22px;margin:34px 0 46px;display:grid}.noteList,.formulaBox,.exampleCard,.quizCard{background:var(--surface);border:1px solid var(--line);box-shadow:var(--shadow-sm);border-radius:18px}.noteList{padding:8px}.note{border-bottom:1px solid var(--line);padding:16px 15px}.note:last-child{border-bottom:0}.note b{margin-bottom:6px;font-weight:750;display:block}.note p{color:var(--muted);max-width:72ch;margin:0;line-height:1.58}.bigPrompt{color:var(--ink);background:var(--blue-soft);border:1px solid oklch(82% .06 255);border-radius:14px;padding:14px 15px;font-weight:600;line-height:1.58}.activity{border:1px solid var(--line);color:var(--muted);background:oklch(97.5% .006 248);border-radius:14px;margin-top:16px;padding:14px;line-height:1.5}.formulaBox{padding:24px}.formulaBox p{color:var(--muted);line-height:1.65}.examplesGrid{grid-template-columns:repeat(2,minmax(0,1fr));gap:14px;margin-top:16px;display:grid}.exampleCard{padding:18px;transition:transform .18s,box-shadow .18s,border-color .18s}.exampleCard:hover{box-shadow:var(--shadow);border-color:oklch(82% .045 255);transform:translateY(-2px)}.exampleTop{color:var(--blue-dark);text-transform:uppercase;letter-spacing:.055em;align-items:center;gap:8px;margin-bottom:12px;font-size:12px;font-weight:800;display:flex}.benefit{color:var(--muted);margin:8px 0 0;font-weight:500;line-height:1.5}.emptyState{flex-direction:column;justify-content:center;max-width:800px;min-height:calc(100vh - 58px);display:flex}.emptyState svg{color:var(--muted);margin-bottom:18px}.emptyState p{color:var(--muted);font-size:18px;line-height:1.6}.notice{background:var(--surface);border:1px solid var(--line);color:var(--muted);border-radius:16px;margin-top:20px;padding:16px}.quizSection{border-top:1px solid var(--line);margin-top:48px;padding-top:36px}.quizIntro{color:var(--muted);max-width:68ch;line-height:1.6}.quizList{grid-template-columns:repeat(2,minmax(0,1fr));gap:14px;margin-top:20px;display:grid}.quizCard{padding:17px}.quizCard h3{margin-bottom:13px;font-size:15.5px;line-height:1.38}.optionList{gap:9px;display:grid}.option{text-align:left;border:1px solid var(--line);cursor:pointer;min-height:48px;color:var(--ink);background:oklch(98.5% .004 248);border-radius:12px;align-items:center;gap:10px;padding:11px 13px;font:600 13.5px/1.38 Aptos,Segoe UI,system-ui;transition:background .15s,border-color .15s,transform .15s;display:flex}.option:hover{background:var(--blue-soft);border-color:oklch(82% .06 255)}.option span{background:var(--panel);width:22px;height:22px;color:var(--muted);border-radius:7px;flex:none;place-items:center;font-size:11px;font-weight:800;display:grid}.option.selected{border-color:var(--blue);background:var(--blue-soft)}.option.selected span{background:var(--blue);color:oklch(98.5% .004 248)}.option.right{background:var(--green-soft);border-color:oklch(74% .09 153)}.option.wrong{background:var(--red-soft);border-color:oklch(75% .09 24)}.quizActions{-webkit-backdrop-filter:blur(16px);backdrop-filter:blur(16px);border:1px solid var(--line);box-shadow:var(--shadow);background:oklch(99.5% .004 248/.94);border-radius:18px;flex-wrap:wrap;align-items:center;gap:10px;margin-top:20px;padding:12px;display:flex;position:sticky;bottom:14px}.scoreBtn,.resetBtn{cursor:pointer;border:0;border-radius:12px;padding:12px 16px;font-weight:800;transition:transform .15s,background .15s}.scoreBtn{background:var(--blue);color:oklch(98.5% .004 248)}.scoreBtn:hover{background:var(--blue-dark);transform:translateY(-1px)}.resetBtn{background:var(--panel);color:var(--ink);border:1px solid var(--line)}.resetBtn:hover{background:var(--panel-2)}.scoreBox{background:var(--surface);border:1px solid var(--line);border-radius:12px;align-items:baseline;gap:10px;margin-left:auto;padding:9px 12px;display:flex}.scoreBox b{font-size:20px}.scoreBox span{color:var(--muted);font-size:13px;font-weight:700}.lessonPager{border-top:1px solid var(--line);justify-content:space-between;gap:12px;margin-top:48px;padding-top:32px;display:flex}.pagerBtn{border:1px solid var(--line);background:var(--surface);color:var(--ink);cursor:pointer;border-radius:10px;align-items:center;gap:8px;min-height:44px;padding:12px 18px;font:700 14px Aptos,Segoe UI,system-ui;transition:background .15s,border-color .15s,box-shadow .15s;display:inline-flex}.pagerBtn:hover:not(:disabled){background:var(--blue-soft);border-color:oklch(82% .06 255)}.pagerBtn:disabled{opacity:.38;cursor:default}.pagerBtn--next{margin-left:auto}@media (width<=980px){.workspace{grid-template-columns:1fr}.sidebar{border-right:0;border-bottom:1px solid var(--line);height:auto;max-height:none;padding:14px;position:relative;overflow:visible}.workspaceName{padding:6px 4px}.search{display:none}.courseMeter{padding:12px}.lessonNav{overscroll-behavior-inline:contain;scroll-snap-type:x proximity;grid-auto-columns:minmax(170px,1fr);grid-auto-flow:column;padding:2px 0 8px;display:grid;overflow-x:auto}.lessonNav p{display:none}.lessonNav button{scroll-snap-align:start;grid-template-columns:32px 1fr;min-height:70px}.lessonStatus{display:none}.contentShell{border-top:0}.topbar{position:sticky;top:0}.twoCol,.examplesGrid,.quizList{grid-template-columns:1fr}.scoreBox{margin-left:0}.lessonPage,.emptyState{padding-top:34px}.lessonNav button.active{transform:translateY(-2px)}.lessonPager{flex-wrap:wrap}.pagerBtn{flex:140px;justify-content:center}}@media (width<=620px){.topbar{flex-direction:column;align-items:flex-start;gap:3px;height:auto;min-height:54px;padding:10px 18px}.lessonPage,.emptyState{padding:28px 16px 64px}h1{letter-spacing:-.03em;font-size:34px}.intro{font-size:17px;line-height:1.55}.docIcon{border-radius:14px;width:50px;height:50px}.callout,.lockedBanner{border-radius:16px;padding:15px 16px}.formulaBox{padding:18px}.quizActions{bottom:8px}.scoreBtn,.resetBtn{flex:140px}.scoreBox{justify-content:space-between;width:100%}.lessonNav{grid-auto-columns:minmax(150px,76vw)}}@media (prefers-reduced-motion:reduce){*,:before,:after{scroll-behavior:auto!important;transition:none!important;animation:none!important}}